EMF Exposure from Selected Laboratory and Office Equipment

Transcription

1 EMF Exposure from Selected Laboratory and Office H. Aniolczyk, P. Politanski, P. Mamrot Nofer s Institute of Occupational Medicine, Lodz, Poland. h_aniol@imp.lodz.pl Abstract. EMF of different frequency ranges occur in the vicinity of a large number of equipment used in laboratories and offices. Research has been conducted in offices as well as in laboratories of research institutes, institutions of higher education, and commercial companies. Over 200 devices have been examined, among them: driers, water and ultrasonic baths, crucible furnaces, spreading mills, bactericidal lamps, fluorescent lamps, desk lamps, air-conditioners, display monitors, printers, Xerox s, filtered power supplies, UPS, socket wiring of the above enumerated devices, and feed system. The above data prove that some of them are sources of unintended EMF of relatively high intensity levels. The study involved a comparative evaluation of obtained data concerning the EMF intensity values with reference to international criteria defining admissible levels for non-occupational and general public exposure, as well as admissible levels of emission of the above specified widely used equipment. 1. Introduction Present-day electro environment, in which people live, is markedly different from its original quality. The characteristic of the occurring EMF has also changed. It is a consequence of development of not only energetics and electric current sources, but also electronics. Electronic economy and information society have been basic factors of the changing style of life and labour. Commerce globalisation and intensive development of mobile telecommunication networks turn our attention to differences in the existing legal solutions limiting exposure of humans to EMF. The differences between ICNIRP 1998 guidelines [1], EN: Council Recommendation 1999 [2] and Polish guidelines in the field of MAI 2001 in occupational environment [3] and in the field of environmental protection [4] amounts to even two orders of magnitude.our interest in electro environment in laboratories and offices stems from reported higher health risk of occurrence of certain forms of malignant tumour, including different forms of leukaemia and brain tumours in people and workers exposed to fields of the frequency 50/60 Hz. In 2001, the commission of experts of the International Agency for Research on Cancer (IARC) qualified electro fields 50 Hz as a probable carcinogenic factor for humans (2B in a 4 grade scale) [5]. Particularly disturbing is a possibility of a higher risk of leukaemia in children living in conditions of higher exposure to electro field of average induction value above 0.3 µt [6] i 0.4 µt [7]. Scientific, industrial, and service laboratories apply a variety of electrical equipment, often engine-powered, and electronic with unknown levels of produced EMF. Similarly, in offices occurs high accumulation of different electrical and electronic devices. Research was carried out for diagnostic purposes and it focused on establishing maximum levels of produced EMF in the immediate vicinity of different laboratory and office equipment. 2. Material and methods 2.1. Registration and interview Research was conducted in laboratories and offices of 2 scientific institutes, two institutions of higher education (polytechnics), and 2 of commercial companies. About 50 different types of equipment were registered for research, including power supply components, such as: sockets and wires, filtered power supply, UPS (Uninterrupted Power Supply), and desk lamps. Also, EMF of 28 office workplaces with the media was studied. Maximum intensity values of electric and field were registered within 0.2 m from the studied equipment. 1

2 2.2. Measuring EMF measurements were made by means of controlling-measuring equipment sets with parameters described in tab. A-F: Table A. Magnetic field meter GAUSSMETER model 9500: Probe type Frequency range Measuring range Transverse probe type STF ser. no BULK 1X 20 Hz 10 khz static field 0.1µT 30 T (0.080 A/m 23.9x10 6 A/m) 3 µt 30 T (2.38 A/m 23.9x10 6 A/m) Table B. Magnetic field meter TESLOMIERZ TH-26 Probe type Frequency range Measuring range Transverse probe with Hall unit type EA Hz 1 khz static field 0.04 mt 2 T (16 A/m 1.6x10 6 A/m) Measuring accuracy ±0.5 ±3.6 % 1 ±0.075 % 1 Measuring accuracy ±2 % Table C. Magnetic field meter MNP-89 Probe type Frequency range Measuring range Measuring accuracy Magnetic field meter 50 Hz 0, A/m ±5% Table D. MEH-1a meter with probes set 1 a AE Hz 50 khz kv/m ± 10% 2, ±3 db 3 1 b AE-43 1 khz 100 khz V/m ± 10% 2, ±3 db 3 2 AS MHz 14 GHz W/m 2 ± 15% 2, ±4 db 3 Table E. MEH-25 meter with probes set W/m 2 ± 3 db 2, ±5 db W/m 2 ± 10% 2, ±3 db 3 1 AS MHz 3 GHz V/m ± 3 db 2, ±5 db V/m ± 10% 2, ±3 db 3 Table F. Zestaw MEH-25 z sondami: 1a AE Hz 50 khz 80 V/m 9.8 kv/m ± 10% 2, ±3 db 3 1b AE khz 500 khz 1.5 V/m 88 V/m ± 10% 2, ±3 db 3 2 AH Hz 1 khz A/m ± 10% 2, ±3 db 3 3. Measurement results 3.1. Laboratory Devices Magnetic field/ induction measurement results Research included 42 laboratory devices used as specific equipment in textile industry laboratories, analytic laboratories, scientific laboratories, and computer rooms (32 VDTs). Figure 1 presents a distribution of VDTs in the computer room of the Technical University. It can be observed that the 1 % of value, dependant to measuring subrange 2 field inaccuracy in free space 3 field inaccuracy within 10 cm from original and secondary radiation sources 2

3 monitors are densely packed, so that students sit behind and next to the neighbouring VTDs, when working with their own computer. As we know, both the area behind and next to VDTs is characterised by the highest level of EMF. Magnetic field intensity measurement results, for comparative reasons presented in induction units, for the studies devices are demonstrated in tab. I. The highest values were observed near: ultracompression generator (300 µt), spreading mill (almost 257 µt), X-ray diffractometer (135 µt). Relatively high values were also near a laboratory drier (60 µt) or a textile dyeing (48 µt). For comparison, near an extinction spectrophotometer induction was 6 µt. In student laboratory conditions, induction amounted to 64 µt at work with VDTs. FIG. 1. Distribution of VDTs in the laboratory computer room of the Technical University. Table I. Most important results of laboratory devices measurements. Air permeability testing Laboratory thread dyeing Automatic ultrasonic wire bonding Planetary mill Centrifuge Resistance testing Climatic chamber Sifter Colour measuring Silk-screen half-automatic printer Compressor Soldering station Crucible furnace Spreading mill Diffractometr cooling system Sterilamp Extinction spectrophotometer Tensile testing Filtering characteristic determining Textile dyeing Flow-soldering furnace (with microwave chamber) Thermal insulation testing Four-compartment washing Two-roller padding Grinding Ultracompression generator Laboratory drier Universal drier Laboratory dyeing Washing Laboratory heating jacket Water baths Laboratory membrane filtering Zone furnace for thick layer basis burning Laboratory thread dyeing Weigher / drier Planetary mill X-ray diffractometr

4 Electric field measurement results Conducted electric field measurements demonstrated that, for 42 studied devices, only in the vicinity of 19% electric field intensity was higher than 150 V/m. Among these devices are: zone furnace for thick layer basis burning (550 V/m), X-ray diffractometer (340 V/m) or laboratory drier (300 V/m). These are values below Polish norms (10 kv/m for general population, 5 kv/m for occupational exposure) and also EU i ICNIRP 1998 (5 kv/m for general population) Office devices Magnetic field intensity/ induction measurement results Research included 189 devices and installations, among others: fluorescent lamps, desk lamps, airconditioners, display monitors, printers, Xerox s, filtered power supply UPS, socket wiring of the above enumerated devices, and feed system. Measurement results are presented in tab. II. The highest induction values were observed near: socket and wires (195 µt) and filtered power supply (180 µt). For comparison, near VDTs 64 µt, Xerox 60 µt, lamp-halogen 50 W - 20 µt. In 28 office workplaces with the media, occurrence of measurable induction values, within the sensitivity of the measuring equipment used, was not observed. Table II. Most important results of office devices measurements. Air conditioner Office workplace with the media Filtered power supply Socket and wires Lamp glow-tube 4x18 W Uninterrupted Power Supply Lamp halogen 50 W VDT Lamp incadescent 60 W Xerox Laser printer Electric field intensity measurement results Conducted electric field measurements demonstrates that for 189 studied devices and installations, the highest electric field intensity values were near: socket and wires 210 V/m, near Lamp halogen 50 W 200 V/m and, for comparison, near air conditioner 140 V/m. 4. EMF in the vicinity of laboratory and office devices in the light of references and recommendations for non-occupational and public exposure Research conducted in laboratories near selected laboratory devices demonstrated that induction level in their vicinity in the worst cases is even 4 times higher than NDN for the general public, according to Polish guidelines it is 75 µt, 3 times according to EU and ICNIRP 1998, according to which it is 100 µt. In the vicinity of all the studied laboratory devices the induction value µt was exceeded. Measurements carried out in the vicinity of office devices and installations showed that for 189 studied devices, only in the vicinity of filtered power supplies and sockets and wires the norm for induction according to Polish guidelines was exceeded almost 2.5 times, and almost 2 times according to EU i ICNIRP 1998 guidelines. In specific conditions, the Polish norm near VDTs may also be exceeded. Except for the vicinity of a lamp incandescent 60 W, induction value µt for the remaining devices and installations was exceeded. Electric field in the vicinity of studied devices did not exceed admissible Polish, EU and ICNIRP 1998 norms. 5. Conclusions Conducted research shows that in the case of some laboratory devices, EMF 50/60 Hz and ELF of values exceeding admissible norms for general public or even for occupational exposure (e.g.: 4

5 ultracompression generator (300 µt), spreading mill (almost 257 µt), X-ray diffractometr (135 µt) may occur. Among office devices and installations, socket and wires (195 µt), and filtered power supply (180 µt) are particularly distinguishable. It must be stressed that such office devices and installations as VDTs 64 µt, lamp-halogen 50 W - 20 µt, socket and wires (195 µt), and filtered power supply can be frequently found in our homes and they are used by children. The problem cannot be neglected due to the reports about a possibility of a higher risk of leukaemia in children living in conditions with higher field exposure of the induction average value above 0.3 µt [6] i 0.4 µt [7]. REFERENCES 1. International Commission on Non Ionizing Radiation Protection (ICNIRP): Guidelines for limiting exposure to time varying electric, and electro fields (up to 300 GHz). Health Physics, 74(4): , (1998). 2. EN: Council Recommendation of 12 July 1999 on the limitation of exposure of the general public to electro fields (0Hz to 300 GHz), Off. J. Eur. Communities 199/519/EC L.199: 59-61, (1999). 3. Ordinance of the Minister of Labour and Social Politics from 29 Nov concerning MAC/MAI of agents harmful to health in the working environment. Journal of Law No 217, pos.1833, (2002). 4. Ordinance of the Minister of Environment from 30 Oct, 2003 concerning admissible EMF levels in environment and control methods of following these levels, Journal of Law. No 192, pos. 1883, (2003). 5. International Agency for Research on Cancer (IARC): Static and extremely-low-frequency (ELF) electric and field, Monograph IARC, 80, IARC Lyon, (2002). 6. Ahlbom A., Day N. at all., A pooled analysis of fields and childhood leukaemia, Brit. J. Cancer, 83: , (2000). 7. Greenland S., Sheppard A.R., Kaune W.Y. at all., A pooled analysis of fields, wire codes, and childhood leukaemia, Childhood Leukaemia - EMF Study Group, Epidemiology, 11(6): , (2000). 5